Orthopedic surgery patients go in and out of the operating room "blind" to the cost of their procedures, researchers say, but the patients often assume doctors are making much more than they really do.

The misperceptions among spinal surgery patients are emblematic of a major barrier to controlling healthcare costs, according to the authors, which is that nobody knows what the costs are.

"You're buying a service, and you don't know what you're getting," the study's lead author, Dr. K. Linnea Welton, told Reuters Health. "I think there's something to be said for a more black-and-white system so patients know what they're buying and they can make more educated decisions."

Welton is an orthopedic surgery resident at the University of Michigan.

Health-policy professor Stephen Shortell of the University of California, Berkeley, also thinks transparency would improve the U.S. healthcare system.

"The underlying message of the study is that the American consumer is blind, has no idea of the cost of healthcare," he told Reuters Health. "It is totally unlike any other sector of the American economy. The system is byzantine."

Healthcare providers and insurers have included in their contracts prohibitions against disclosing prices and payments, though some states have begun to outlaw the gag clauses, added Shortell, who was not involved in the new study.

To get a sense of what orthopedic surgery patients knew or believed about surgeon reimbursements, Welton and her colleagues mailed 12-question surveys to 385 patients who underwent spine procedures from 2010 to 2011. Only 103 of the patients, or 27 percent, responded to the surveys.

About three quarters of the respondents had undergone a major procedure on the spine, such as cervical fusion or lumbar fusion, and a quarter had minor procedures such as discectomy.

Of the respondents who underwent minor surgery, 62 percent believed their surgeons earned thousands of dollars more for the procedures than they did, according to the results published in The Spine Journal.

For minor procedures, patients estimated reimbursement was between $5,000 and $10,000, whereas the highest reimbursement for any minor procedure from Medicare was $1,363 and from a private insurer, $2,038.

Of the respondents who underwent major surgery, 28 percent estimated that insurance compensated their surgeons something above $15,000 - which is more than $8,000 in excess of the highest actual reimbursement.

In addition, the patients assumed the surgeons were paid additional fees for postoperative visits, when in reality the initial payments covered all surgical care for three months, Welton said.

Many survey participants also overestimated their surgeons' annual salaries, Welton said. Some 22 percent of respondents estimated their surgeons earned between $500,000 and $750,000 annually. In fact, 68 percent of orthopedic spine surgeons earn less than $750,000, Welton and her colleagues point out.

According to a 2012 survey of doctors, orthopedic surgeons earned more than physicians in any other specialty, with a median compensation of $563,074.

"I believe the American public is correct to believe that orthopedic surgeons are overpaid, because they are," labor economist J. Paul Leigh told Reuters Health in an email.

In a 2010 study, Leigh says he showed that orthopedic surgeons earned roughly $2.2 million more in their lifetimes than family practice physicians, after controlling for varying length of residency years, work hours, gender, age and other salary predictors.

A professor at the Center for Healthcare Policy and Research at the University of California, Davis, Leigh was not involved in the current study.

Welton said the intent of her study was not to push for higher salaries for orthopedic surgeons but to shine light on the knowledge gaps.

"It's not to say we should be paid more," she said. "It's to say patients value what we do, and we don't as a population have a good idea of how our healthcare dollars are allocated."

"Most Americans value their personal physicians," Shortell said. "But the costs of healthcare in the U.S. are so high, and the outcomes are so low compared to other countries. The issue is we're not getting value for the money we're spending."